Re: Makefile rule differences with base 3.14 vs 3.15+ in ADCore build with pvi

[Andrew Johnson via Tech-talk <tech-talk@aps.anl.gov>]

    Hi Gary,

On 8/10/22 7:35 AM, Yendell, Gary (DLSLtd, RAL, LSCI) via Tech-talk wrote:

I am currently working on a proposed change to ADCore to use pvi to generate template and header files during the build.

    Why should that go into ADCore? You would appear to be adding a
    dependency which (currently at least) only your site might need. The
    EPICS build system allows support modules to publish CONFIG_* and
    RULES_* files that downstream modules (i.e. other modules that point
    to this module in their configure/RELEASE file) will include
    automatically, although some aspects of that did change slightly
    somewhere in the 3.14-3.15 timescale. I would recommend you look
    into making your changes in a way that downstream IOCs only need to
    add your module to obtain the additional build functionality. The
    EPICS State Notation Compiler/Sequencer module does this in its more
    recent releases, look at its cfg/RULES_SNCSEQ file for one of the
    earlier examples, and ask here for more details if you do go this
    route.
    
    BTW I know nothing about pvi, we don't use it here so some things in
    my answer may reflect my ignorance about what it does.

This works on 3.14 locally and in GitHub Actions with ci-scripts. The files are generated during the build, and it completes. If I change a yaml file only the relevant files are regenerated and rebuilt against. However, in CI on 3.15 (and 7) I see two problems.

1. Rules are not being run to regenerate existing files even though the sources are newer than the targets.

When the files exist, it does not consider the yaml file as a pre-requisite at all in 3.15, where it does in 3.14, so it just installs the existing file. The rules do run on 3.15 if the targets do not exist at all, but in a preliminary step before the rule for installing to db/ - see here.

Is it because of slightly strange rules to generate the files in the source location and then copy them? Maybe the dependency isn't tracked properly in 3.15? The pvi rules are defined here.

    One major change in the build system between 3.14 and 3.15 was that
    in 3.15 and beyond we expect anyone adding build rules to also
    provide rules for creating dependency $(DEP) i.e. .d files for their
    build targets. You might need some conditionals to only enable those
    dependency rules on 3.15 and later builds, but they are easy to add.
    I think this is probably causing both problems that you're seeing,
    you need to provide rules to create your template.d files, and when
    you do that you can include the yaml file(s) as one of the
    dependencies, which will then cause later modifications to that file
    to run the regeneration rules automatically.
    
    You can compare the equivalent sections of the
    Base/configure/RULES_BUILD files for examples of creating the $(DEP)
    files.
    
    HTH,
    
    - Andrew
-- 
Complexity comes for free, Simplicity you have to work for.